package org.bouncycastle.asn1.x509;

import java.util.ArrayList;
import java.util.List;

import org.bouncycastle.asn1.ASN1BitString;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.asn1.ASN1Object;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.DERTaggedObject;
import org.bouncycastle.asn1.x500.X500Name;
import org.bouncycastle.util.AggregateRuntimeException;
import org.bouncycastle.util.Properties;

/**
 * The TBSCertificate object.
 *  
 * TBSCertificate ::= SEQUENCE {
 *      version          [ 0 ]  Version DEFAULT v1(0),
 *      serialNumber            CertificateSerialNumber,
 *      signature               AlgorithmIdentifier,
 *      issuer                  Name,
 *      validity                Validity,
 *      subject                 Name,
 *      subjectPublicKeyInfo    SubjectPublicKeyInfo,
 *      issuerUniqueID    [ 1 ] IMPLICIT UniqueIdentifier OPTIONAL,
 *      subjectUniqueID   [ 2 ] IMPLICIT UniqueIdentifier OPTIONAL,
 *      extensions        [ 3 ] Extensions OPTIONAL
 *      }
 * </pre>
 * <p>
 * Note: issuerUniqueID and subjectUniqueID are both deprecated by the IETF. This class
 * will parse them, but you really shouldn't be creating new ones.
 */
public class TBSCertificate
    extends ASN1Object
{
    ASN1Sequence            seq;

    ASN1Integer             version;
    ASN1Integer             serialNumber;
    AlgorithmIdentifier     signature;
    X500Name                issuer;
    Validity                validity;
    X500Name                subject;
    SubjectPublicKeyInfo    subjectPublicKeyInfo;
    ASN1BitString           issuerUniqueId;
    ASN1BitString           subjectUniqueId;
    Extensions              extensions;

    public static TBSCertificate getInstance(
        ASN1TaggedObject obj,
        boolean          explicit)
    {
        return getInstance(ASN1Sequence.getInstance(obj, explicit));
    }

    public static TBSCertificate getInstance(
        Object  obj)
    {
        if (obj instanceof TBSCertificate)
        {
            return (TBSCertificate)obj;
        }
        else if (obj != null)
        {
            return new TBSCertificate(ASN1Sequence.getInstance(obj));
        }

        return null;
    }

    private TBSCertificate()
    {
        // used by reviewStructure() to drive parse() in collect-all mode;
        // the resulting (possibly invalid) instance is never published.
    }

    private TBSCertificate(
        ASN1Sequence seq)
    {
        parse(seq, null);
    }

    /**
     * Re-run the parse of a candidate tbsCertificate SEQUENCE collecting every problem the
     * strict {@code getInstance([])} path would have thrown, instead of stopping at the
     * first. The strict path and this share one parse method (see {@link #parse}); the only
     * difference is the error sink. Intended for diagnostic/reporting tooling
     * (e.g. {@code org.bouncycastle.cert.X509CertificateReviewer}, github #1508); it does
     * not relax any rule and does not publish a partially-parsed certificate.
     *
     * @param seq the candidate tbsCertificate SEQUENCE.
     * @return the exceptions the strict path would have thrown, one per problem, in parse
     *         order (empty if none).
     */
    public static List reviewStructure(ASN1Sequence seq)
    {
        List errors = new ArrayList();
        try
        {
            new TBSCertificate().parse(seq, errors);
        }
        catch (RuntimeException e)
        {
            // a structural sub-field failure (e.g. a field of the wrong ASN.1 type) aborts
            // enumeration; surface the exception so the caller still learns something went wrong.
            errors.add(e);
        }
        return errors;
    }

    private void parse(ASN1Sequence seq, List errors)
    {
        int         seqStart = 0;

        this.seq = seq;

        //
        // some certficates don't include a version number - we assume v1
        //
        if (seq.getObjectAt(0) instanceof ASN1TaggedObject)
        {
            version = ASN1Integer.getInstance((ASN1TaggedObject)seq.getObjectAt(0), true);
        }
        else
        {
            seqStart = -1;          // field 0 is missing!
            version = ASN1Integer.ZERO;
        }

        boolean isV1 = false;
        boolean isV2 = false;

        if (version.hasValue(0))
        {
            isV1 = true;
        }
        else if (version.hasValue(1))
        {
            isV2 = true;
        }
        else if (!version.hasValue(2))
        {
            reportProblem(errors, "version number not recognised");
            // collecting only: treat an unrecognised version as v3 so the v1/v2 profile
            // checks below are not spuriously reported on top of the bad-version one.
        }

        serialNumber = ASN1Integer.getInstance(seq.getObjectAt(seqStart + 1));

        signature = AlgorithmIdentifier.getInstance(seq.getObjectAt(seqStart + 2));
        issuer = X500Name.getInstance(seq.getObjectAt(seqStart + 3));
        // RFC 5280 sec. 4.1.2.4: certificate issuer MUST be a non-empty DN.
        if (issuer.size() == 0)
        {
            reportProblem(errors, "certificate issuer is an empty distinguished name");
        }
        validity = Validity.getInstance(seq.getObjectAt(seqStart + 4));
        subject = X500Name.getInstance(seq.getObjectAt(seqStart + 5));
        subjectPublicKeyInfo = SubjectPublicKeyInfo.getInstance(seq.getObjectAt(seqStart + 6));

        int extras = seq.size() - (seqStart + 6) - 1;
        if (extras != 0 && isV1)
        {
            reportProblem(errors, "version 1 certificate contains extra data");
        }

        while (extras > 0)
        {
            ASN1TaggedObject extra = (ASN1TaggedObject)seq.getObjectAt(seqStart + 6 + extras);

            switch (extra.getTagNo())
            {
            case 1:
                issuerUniqueId = ASN1BitString.getInstance(extra, false);
                break;
            case 2:
                subjectUniqueId = ASN1BitString.getInstance(extra, false);
                break;
            case 3:
            {
                if (isV2)
                {
                    reportProblem(errors, "version 2 certificate cannot contain extensions");
                }
                ASN1Sequence extSeq = ASN1Sequence.getInstance(extra, true);
                if (errors == null)
                {
                    extensions = Extensions.getInstance(extSeq);
                }
                else
                {
                    // collecting: enumerate every repeated/malformed extension rather than
                    // aborting on the first, using Extensions' own shared checks.
                    List extProblems = Extensions.reviewStructure(extSeq);
                    if (!extProblems.isEmpty())
                    {
                        errors.add(new AggregateRuntimeException("invalid extension(s)", extProblems));
                    }
                }
                break;
            }
            default:
                reportProblem(errors, "Unknown tag encountered in structure: " + extra.getTagNo());
            }
            extras--;
        }
    }

    /**
     * Report a parse problem: in strict mode ({@code errors == null}) throw immediately as
     * the legacy parse always has; in collect mode record the exception and continue. Because
     * the strict sink throws here, no statement after a call site executes in strict mode, so
     * strict parsing behaviour and messages are unchanged.
     */
    private static void reportProblem(List errors, String message)
    {
        IllegalArgumentException problem = new IllegalArgumentException(message);
        if (errors == null)
        {
            throw problem;
        }
        errors.add(problem);
    }

    public TBSCertificate(ASN1Integer version, ASN1Integer serialNumber, AlgorithmIdentifier signature,
        X500Name issuer, Validity validity, X500Name subject, SubjectPublicKeyInfo subjectPublicKeyInfo,
        ASN1BitString issuerUniqueId, ASN1BitString subjectUniqueId, Extensions extensions)
    {
        if (serialNumber == null)
        {
            throw new NullPointerException("'serialNumber' cannot be null");
        }
        if (signature == null)
        {
            throw new NullPointerException("'signature' cannot be null");
        }
        if (issuer == null)
        {
            throw new NullPointerException("'issuer' cannot be null");
        }
        if (issuer.size() == 0)
        {
            throw new IllegalArgumentException("certificate issuer is an empty distinguished name");
        }
        if (validity == null)
        {
            throw new NullPointerException("'validity' cannot be null");
        }
        if (subject == null)
        {
            throw new NullPointerException("'subject' cannot be null");
        }
        if (subjectPublicKeyInfo == null)
        {
            throw new NullPointerException("'subjectPublicKeyInfo' cannot be null");
        }

        this.version = version != null ? version : ASN1Integer.ZERO;
        this.serialNumber = serialNumber;
        this.signature = signature;
        this.issuer = issuer;
        this.validity = validity;
        this.subject = subject;
        this.subjectPublicKeyInfo = subjectPublicKeyInfo;
        this.issuerUniqueId = issuerUniqueId;
        this.subjectUniqueId = subjectUniqueId;
        this.extensions = extensions;

        this.seq = null;
    }

    public int getVersionNumber()
    {
        return version.intValueExact() + 1;
    }

    public ASN1Integer getVersion()
    {
        return version;
    }

    public ASN1Integer getSerialNumber()
    {
        return serialNumber;
    }

    public AlgorithmIdentifier getSignature()
    {
        return signature;
    }

    public X500Name getIssuer()
    {
        return issuer;
    }

    public Validity getValidity()
    {
        return validity;
    }

    public Time getStartDate()
    {
        return validity.getNotBefore();
    }

    public Time getEndDate()
    {
        return validity.getNotAfter();
    }

    public X500Name getSubject()
    {
        return subject;
    }

    public SubjectPublicKeyInfo getSubjectPublicKeyInfo()
    {
        return subjectPublicKeyInfo;
    }

    public ASN1BitString getIssuerUniqueId()
    {
        return issuerUniqueId;
    }

    public ASN1BitString getSubjectUniqueId()
    {
        return subjectUniqueId;
    }

    public Extensions getExtensions()
    {
        return extensions;
    }

    public ASN1Primitive toASN1Primitive()
    {
        if (seq != null)
        {
            if (Properties.getPropertyValue("org.bouncycastle.x509.allow_non-der_tbscert") != null)
            {
                if (Properties.isOverrideSet("org.bouncycastle.x509.allow_non-der_tbscert"))
                {
                    return seq;
                }
            }
            else
            {
                return seq;
            }
        }

        ASN1EncodableVector v = new ASN1EncodableVector(10);

        // DEFAULT Zero
        if (!version.hasValue(0))
        {
            v.add(new DERTaggedObject(true, 0, version));
        }

        v.add(serialNumber);
        v.add(signature);
        v.add(issuer);
        v.add(validity);
        v.add(subject);
        v.add(subjectPublicKeyInfo);

        // Note: implicit tag
        if (issuerUniqueId != null)
        {
            v.add(new DERTaggedObject(false, 1, issuerUniqueId));
        }

        // Note: implicit tag
        if (subjectUniqueId != null)
        {
            v.add(new DERTaggedObject(false, 2, subjectUniqueId));
        }

        if (extensions != null)
        {
            v.add(new DERTaggedObject(true, 3, extensions));
        }

        return new DERSequence(v);
    }
}
